1. Field of the Application
This application relates generally to test and diagnostic systems for motor vehicles. More particularly, the application relates to an automated process for retrieving diagnostic vehicle information relative to returned trouble codes from one or more vehicle components under diagnosis. While the application is described in the context of a vehicle diagnostic system and method, the principles of the present application are equally applicable for any testing and diagnostic systems, including non-motor vehicle equipment, as long as the equipment under diagnosis stores trouble codes relative to an error condition.
2. Description of the Related Art
Motor vehicles are becoming highly computerized products. In recent years, the control of internal combustion engines has branched away from traditional mechanical linkages and analog approaches to electronic or microprocessor-based control systems. In a typical modern motor vehicle, the operation of the combustion engine is controlled by an engine control module (ECM) which receives a variety of input signals and outputs signals for monitoring and controlling various components of the engine. For example, the ECM can send signals to a fuel system for controlling the air/fuel mix sent to the engine cylinders. The ECM may also receive and store signals from various sensors throughout the engine and drive train. For example, the sensors may provide signals indicative of engine speed, fuel/air mix, intake and exhaust pressure, engine operating temperatures, fluid levels, and the like.
The ECM may retain a portion of this data in memory, providing a history of engine performance, operating parameters, and error indicators. An external interface to the ECM and its stored data is provided at a location accessible to a repair technician. The information stored in the ECM can be downloaded via the external interface at predetermined intervals in the engine life, when there are noticeable degradations in engine performance, or when critical trouble codes are received and externally indicated to an operator of the motor vehicle. The downloaded information can then be analyzed by a repair technician to evaluate the engine performance or error conditions, and thereby make informed recommendations for servicing of the engine.
In order to facilitate the retrieval of trouble codes and diagnostic information from an ECM or similar circuit, a number of different types of trouble code retrieval tools have been developed to assist in the diagnosis and repair of fault conditions reported by the ECM's. Such a retrieval tool can typically be connected to the ECM's external interface and provides a display for reporting the data stored in the ECM. For example, a retrieval tool may obtain one or more pieces of information about the vehicle's engine noted above, including fluid levels, operating temperatures, fuel/air mixes, in addition to other information reported by the transmission, air conditioning, braking, and/or power systems.
Once the trouble codes are retrieved, the codes can be entered into a diagnostic tool that utilizes the trouble code information to form diagnostic trees, which are created by Original Equipment Manufacturers (OEMs). Diagnostic tools may allow a repair technician to enter information, including fault symptoms, into the diagnostic tool to be used in conjunction with the information downloaded from the vehicle's on-board computer to diagnose and assist in the repair of fault conditions in the vehicle.
Manufacturers publish repair manuals, including diagnostic trees, exploded part diagrams, and the like, to aid in the diagnosis and repair of problems discovered by such diagnostic tools. For example, based upon selected faults, a diagnostic tree could present the reader with a list of tests to be performed to diagnose the cause or causes of the faults. The tests can be listed in the order in which they would most likely be effective in diagnosing the vehicle faults, based upon a manufacturer's information and previous repair and diagnosis experience with this type of vehicle, for example. The repair manuals may be available in hard copy or accessible via the Internet in a computer viewable format.
In practice, a repair technician then sorts through the repair information in order to find the information pertinent to the specific equipment being diagnosed. Though technicians see this as part of their job, it can be a time consuming process. The time element increases a cost of repair and delays the turn-around time for returning the motor vehicle under repair to service. This is especially important in the trucking industry, where a truck must be on the road to be generating income, or where a disabled truck is carrying a time-sensitive load such as perishable food.